I have the exact same thing and I'm also without kids. A soft mass of walnut texture (squidgy and not painful). One day my vaginal walls were smooth and firm and the next, I had developed this squidgy walnut area. 
It's always best to get these things checked out but ive had it for 10 years. I have had plenty of examinations in that area and nobody has ever said anything so assuming it's just a mini collapse of my vaginal walls as ive got older. It is exactly how you describe (not really a mass...more a soft squidgy of extra tissue) 

Hello, thank you for your response. 
I will see a private gynaecologist  today. I hope to find the solution to this. I will probably need some scans tests to find out the cause. 
have a great day
 

Hello, thank you for your response. 
I will see a private gynaecologist  today. I hope to find the solution to this. I will probably need some scans tests to find out the cause. 
have a great day